“The Berrisford Agenda” is episode eleven of season two of Dark Angel.
Alec comes along on a delivery with Max to get out of the office. When they arrive at the destination, he recognises it and wants to leave.
The mansion they delivered to is owned by someone who Alec was sent to kill when he belonged to Manticore.
He had been sent to infiltrate the house of a Manticore supplier who was causing problems. Whilst there, he got a bit involved with the daughter. Probably rather more than he should have been, given his mission.
Precisely what happened at the house isn’t made clear until close to the end, but someone at the house recognised Alec and sent people after him. Alec also reveals a different side of himself.